如何使用GD庫將文本寫在圖像上

Question

如何使用PHP圖像生成函數將長文本置於圖像上，選擇區域，水平對齊，垂直對齊以及讓長文本自動換行在選定的區域正確嗎？

這可以複製並在其他語言中變得有用嗎？

Answer 1

PHP函數imagettftext（...）可以編寫文本，但不支持長文本的包裝，因此您必須將文本分成單詞，並且爲每個單詞調用imagettfbbox（...）來計算單詞邊界和測試這個詞是否應該放在新的一行上。

要知道文本的總高度，爲了能夠垂直對齊文本，必須將渲染推遲到最後。

這是代碼。

DEMO USAGE

<?php 


// Image params 

    $imgWidth = 240; 
    $imgHeight = 900; 


// Text params 

    $text='Tanto va la gatta al lardo che ci lascia lo zampino!'; 
    $drawFrame=array(10,340,$imgWidth-10,$imgHeight-140); 
    $fontType = 'ArialBlack.ttf'; 
    $fontSize = 30; 
    $lineHeight=32; 
    $wordSpacing=' '; 
    $hAlign=0; // -1:left 0:center 1:right 
    $vAlign=0; // -1:top 0:middle 1:bottom 


// allocate 

    $img = imagecreatetruecolor($imgWidth,$imgHeight); 
    $background = imagecolorallocate($img, 78,129,154); 
    $textColor = imagecolorallocate($img, 255,255,255); 

// debug show text area 

    $area_color = imagecolorallocate($img, 255,0,0); 
    imagerectangle ($img, $drawFrame[0], $drawFrame[1], $drawFrame[2], $drawFrame[3], $area_color); 

// write text 

    wrapimagettftext($img, $fontSize, $drawFrame, $textColor,$fontType, $text, '100%',' ',$hAlign,$vAlign); 

// output image 

    header("Content-type: image/png"); 
    imagepng($img); 
    imagecolordeallocate($img, $textColor); 
    imagecolordeallocate($img, $background); 

?> 

主要功能

<?php 


function wrapimagettftext($img, $fontSize, $drawFrame, $textColor,$fontType, $text, $lineHeight='',$wordSpacing='',$hAlign=0,$vAlign=0) { 

    if($wordSpacing===' ' || $wordSpacing==='') { 
     $size = imagettfbbox($fontSize, 0, $fontType, ' '); 
     $wordSpacing=abs($size[4]-$size[0]); 
    } 
    $size = imagettfbbox($fontSize, 0, $fontType, 'Zltfgyjp'); 
    $baseHeight=abs($size[5]-$size[1]); 
    $size = imagettfbbox($fontSize, 0, $fontType, 'Zltf'); 
    $topHeight=abs($size[5]-$size[1]); 

    if($lineHeight==='' || $lineHeight==='') { 
     $lineHeight=$baseHeight*110/100; 
    } else if(is_string($lineHeight) && $lineHeight{strlen($lineHeight)-1}==='%') { 
     $lineHeight=floatVal(substr($lineHeight,0,-1)); 
     $lineHeight=$baseHeight*$lineHeight/100; 
    } else { 

    } 

    $usableWidth=$drawFrame[2]-$drawFrame[0]; 
    $usableHeight=$drawFrame[3]-$drawFrame[1]; 

    $leftX=$drawFrame[0]; 
    $centerX=$drawFrame[0]+$usableWidth/2; 
    $rightX=$drawFrame[0]+$usableWidth; 

    $topY=$drawFrame[1]; 
    $centerY=$drawFrame[1]+$usableHeight/2; 
    $bottomY=$drawFrame[1]+$usableHeight; 

    $text = explode(" ", $text); 

    $line_w=-$wordSpacing; 
    $line_h=0; 
    $total_w=0; 
    $total_h=0; 
    $total_lines=0; 

    $toWrite=array(); 
    $pendingLastLine=array(); 

    for($i=0;$i<count($text);$i++) { 
     $size = imagettfbbox($fontSize, 0, $fontType, $text[$i]); 

     $width = abs($size[4] - $size[0]); 
     $height = abs($size[5] - $size[1]); 

     $x = -$size[0]-$width/2; 
     $y = $size[1]+$height/2; 

     if($line_w+$wordSpacing+$width>$usableWidth) { 
      $lastLineW=$line_w; 
      $lastLineH=$line_h; 

      if($total_w<$lastLineW) $total_w=$lastLineW; 
      $total_h+=$lineHeight; 

      foreach($pendingLastLine as $aPendingWord) { 

       if($hAlign<0) $tx=$leftX+$aPendingWord['tx']; 
       else if($hAlign>0) $tx=$rightX-$lastLineW+$aPendingWord['tx']; 
       else if($hAlign==0) $tx=$centerX-$lastLineW/2+$aPendingWord['tx']; 

       $toWrite[]=array('line'=>$total_lines,'x'=>$tx,'y'=>$total_h,'txt'=>$aPendingWord['txt']); 
      } 
      $pendingLastLine=array(); 

      $total_lines++; 
      $line_w=$width; 
      $line_h=$height; 

      $pendingLastLine[]=array('tx'=>0,'w'=>$width,'h'=>$height,'x'=>$x,'y'=>$y,'txt'=>$text[$i]); 
     } else { 

      $line_w+=$wordSpacing; 
      $pendingLastLine[]=array('tx'=>$line_w,'h'=>$width,'w'=>$height,'x'=>$x,'y'=>$y,'txt'=>$text[$i]); 
      $line_w+=$width; 
      if($line_h<$height) $line_h=$height; 
     } 
    } 

    $lastLineW=$line_w; 
    $lastLineH=$line_h; 

    if($total_w<$lastLineW) $total_w=$lastLineW; 
    $total_h+=$lineHeight; 

    foreach($pendingLastLine as $aPendingWord) { 

     if($hAlign<0) $tx=$leftX+$aPendingWord['tx']; 
     else if($hAlign>0) $tx=$rightX-$lastLineW+$aPendingWord['tx']; 
     else if($hAlign==0) $tx=$centerX-$lastLineW/2+$aPendingWord['tx']; 

     $toWrite[]=array('line'=>$total_lines,'x'=>$tx,'y'=>$total_h,'txt'=>$aPendingWord['txt']); 
    } 
    $pendingLastLine=array(); 
    $total_lines++; 

    $total_h+=$lineHeight-$topHeight; 

    foreach($toWrite as $aWord) { 

     $posx = $aWord['x']; 

     if($vAlign<0) $posy=$topY+$aWord['y']; 
     else if($vAlign>0) $posy=$bottomY-$total_h+$aWord['y']; 
     else if($vAlign==0) $posy=$centerY-$total_h/2+$aWord['y']; 

     imagettftext($img, $fontSize, 0, $posx, $posy , $textColor, $fontType, $aWord['txt']); 

    } 
} 
?>